PROJECT SUMMARY/ABSTRACT The majority of breast cancer survivors experience sexual concerns impacting their sexual function. These concerns can have long-term negative consequences on survivors? relationships and psychological well-being. Yet unlike other aspects of quality of life (QOL) that tend to improve over time for breast cancer survivors, sexual concerns do not typically resolve without intervention. Addressing breast cancer survivors? sexual concerns and improving their sexual function is thus critical to their long-term adjustment. However, there is a lack of empirically supported interventions targeting sexual function in breast cancer survivors. Because of the integral role that the couple relationship plays in women?s sexual function, an intervention that systematically involves the partner is likely to be an effective approach for addressing sexual concerns and improving survivor outcomes. Previously, we demonstrated that a 4-session couple-based Intimacy Enhancement (IE) intervention delivered via telephone improved sexual and relationship outcomes for couples facing colorectal cancer. After adapting the IE intervention to meet the needs of breast cancer survivors, data from a pilot RCT in 29 breast cancer survivors and their partners suggest the IE intervention to be feasible and acceptable, 2ith promising effect sizes on patient sexual function and related patient and partner outcomes. The main objective of the proposed study is to evaluate the efficacy of the novel couple-based IE intervention in 120 breast cancer survivors and their intimate partners. Couples will be randomized to receive either the IE intervention or to a previously tested attention control condition (Living Healthy Together; LHT). Assessments will be conducted with patients and partners at pre-treatment, post-treatment, and 3- and 6-months follow up. The primary aim (Aim 1) is to examine whether the IE intervention leads to a significantly greater improvement in patient sexual function compared to the LHT intervention. The two secondary aims are to evaluate whether the IE intervention leads to significantly greater improvements in partner sexual function (Aim 2a) and in patient and partner relationship intimacy and quality and psychological distress (Aim 2b), compared to the LHT condition. We will also examine whether treatment effects on patient sexual function are mediated by sexual communication and self-efficacy for coping with sexual concerns (Aim 3). Finally, to inform potential next steps in intervention development, an exploratory aim is to examine whether patient age or race/ethnicity moderate IE intervention effects on patient sexual function. This study will be the first randomized controlled trial of a couple-based intervention targeting sexual function for breast cancer survivors, as well as the first to first to evaluate mechanisms by which a psychosocial intervention improves sexual function for women with cancer. Findings of this study could have a significant impact on clinical care for women with breast cancer, on the theory guiding cancer-related sexual rehabilitation, and ultimately, on the health and well-being of women diagnosed with breast cancer and their intimate partners.